The present invention relates generally to image reproducing systems, and more particularly relates to electrostatic latent image formation and development systems for enhancing latent image development.
Conventional electrostatographic copying and printing systems selectively charge and expose a photoreceptive member in an image-wise manner. This generates an input electrostatic latent image on the receiving member. The latent image is subsequently developed into a visible image by depositing charged development material on the surface of the receiving member. The developing material typically comprises carrier granules having marking or toner particles that electrically adhere to the latent image. The developed image is subsequently transferred, either directly or indirectly, from the receiving member to a copy substrate, such as paper or the like.
The above-described electrostatographic printing process is well known and has been implemented in various forms in the marketplace. Analogous processes also exist in other electrostatic printing applications, such as, for example, ionographic printing and reproduction where a charge is deposited in an image-wise configuration on a dielectric charge retentive surface, as well as in other electrostatic printing systems where a charge carrying medium is adapted to carry an electrostatic latent image.
In the foregoing electrostatographic printing processes, a development material, such as a toner cake, can be applied to the receiving member. The image quality in the printing process varies significantly due to numerous conditions affecting latent image formation on the toner cake as well as development of the image formed thereon. For example, the presence of excess fluid in the toner cake or the application of a relatively thick toner cake layer on the receiving member decreases image quality by exacerbating image "blooming" problems that are generally prevalent during copying. Moreover, the appropriate amount of fluid and the thickness of the toner cake necessary to promote relatively good image development is generally incompatible with the thickness and fluid content of the toner cake layer required for proper and adequate image separation and development.
An example of a prior ionographic image development system for creating a latent image in a toner layer on a support member is disclosed in U.S. Pat. No. 5,966,570, the contents of which are herein incorporated by reference. The system employs a charging device for directing a charge stream, which corresponds to the latent image, at the support member. The charge stream leads to image-wise charging of the toner layer, such that the toner layer becomes the latent image carrier. The toner layer is subsequently developed and transferred to a copy substrate.
An example of a prior image development system for creating a latent image in a toner layer on a support member is disclosed in U.S. Pat. No. 5,826,147, the contents of which are herein incorporated by reference. In this system, the support member is a photoreceptive member rather than a charge retentive member. Similar to the ionographic system, the present system can form a latent image in a layer of marking material on the photoreceptive member. A wide beam ion source is employed for directing free mobile ions at the support member. The latent image causes the free mobile ions to flow in an image-wise ion stream corresponding to the latent image. The ion stream leads to image-wise charging of the toner layer, such that the toner layer becomes the latent image carrier. The toner layer is subsequently developed and transferred to a copy substrate.